1. Field of the Invention
This invention relates to a film sheet load magazine, and more particularly to a film sheet load magazine in which a stack of superimposed sheets are retained in the magazine with at least central portions of the sheets in a curved, essentially semi-circular configuration, to provide a compact and light-weight device of large sheet-holding capacity which is operable independent of orientation with respect to gravity, enables a stack of superimposed sheets to be loaded into the magazine en masse without interposing separators between the sheets, facilitates feeding of the sheets in succession one at a time to an associated mechanism, such as an x-ray film exposure device, in a reliable manner at high speed, provides an operator with an accurate indication of the number of films remaining in the magazine, and whether a sufficient number of sheets remain for a particular processing operation, and also inhibits operation of an associated device if there are insufficient sheets.
2. Description of the Prior Art
U.S Pat. No. 4,782,504 to O. K. Weber et al, which is assigned to the same assignee as the subject patent application, discloses a programmable X-ray film changer for use, for example, in making serial X-ray images of a patient in angiographic medical diagnostic studies. In that patent, a stack of films are stored horizontally disposed in a load magazine and fed from the magazine in succession one at a time into a film exposure device. For this purpose, separators are used to separate one film from another physically while they are being stored in the load magazine. In the feeding of one of the films, a drive mechanism, which includes an arm with a hook, is operated from the film exposure device and engages the top film in the stack at its trailing end, and, in essence, pushes the film into the film exposure device. Further, in load magazines of the type disclosed in that patent, and other known film changers, in order for an operator to know how many films remain in the magazine at any one time, the operator presets an indicator when the magazine is loaded.
Another type of presently known film sheet load magazine is one in which film sheets are stored in the magazine in an essentially curved configuration. For example, the British Patent No. 1,189,914 discloses a film load magazine in which the films are stored in the magazine in a curved condition in substantially semicircular grooves formed in opposite side walls of the magazine, with the grooves having curved central portions, straight horizontal lower end portions, and upwardly inclined opposite upper end portions. The films are fed out of the inside of the resultant curved stack by a spring-loaded friction member which is mounted on an intermittently driven rotatable shaft extending centrally and transversely across the magazine essentially diametrically with respect to the films.
Similarly, U.S. Pat. No. 4,355,798 to F. Villa discloses a film sheet load magazine in the form of a curved spout having a curved outer wall of a relatively high degree of curvature and a curved inner wall of reduced curvature. In loading the films into the magazine, a hinged and flanged end portion of the outer wall is pivoted upward and a stack of films is inserted into the magazine against the outer wall in superimposed relationship, after which the hinged wall portion is returned to a lower position so that a flange thereon abuts outer ends of the stack. During the insertion of the stack of film sheets into the magazine, the films slide upon one another to remove the tendency of the films to adhere together in subsequent feeding of the films. In a film feeding operation, the films are separated by a stripping device engaging an outer end portion of the lowermost film in the stack, whereupon this film, because of its elasticity and curvature in the magazine, moves forward to a mechanism for feeding the film into a film exposure station.
U.S. Pat. No. 4,447,053 to M. Wager et al discloses several embodiments of a film sheet load magazine in each of which the films are stored in a curved condition. To load the films into the magazine, the films are inserted one at a time into screw threads of a rotatable screw-threaded drive member and the drive member is rotated to move the inserted films downwardly in the magazine. To feed the films out of the magazine one at a time to a film exposure station, the drive member is rotated in a reverse direction to raise each film upward into a position into engagement with a feed mechanism which is external of the magazine.
U.S. Pat. No. 4,712,227 to H. Warden discloses a film sheet load magazine in which the films are stored in a curved condition with trailing ends of the films engaged against a retaining flange and leading ends of the films positioned in a separator mechanism. Thus, as in the case of the aforementioned Wager et al patent, the films must be loaded into the magazine with the leading ends of the films engaged between the separators, one at a time. In a film feeding operation, each film is fed from the magazine by an internal drive mechanism to an external drive mechanism which then feeds the film to a film exposure device.
Accordingly, a need exists for a film sheet load magazine which is of compact, light-weight construction, has a large sheet-holding capacity, is operable independent of orientation with respect to gravity, enables a stack of superimposed sheets to be loaded into the magazine simultaneously without interposing separators between the sheets, facilitates feeding of the sheets from the magazine in succession one at a time in a rapid and reliable manner, provides an accurate indication of the number of sheets remaining in the magazine at any one time and whether a sufficient number of sheets remain for a particular processing operation, and also inhibits operation of an associated device if there are insufficient sheets, and a purpose of this invention is to provide a film sheet load magazine having these characteristics.